/Engine/Source/Editor/UnrealEd/Classes/Editor/EditorEngine.h
Overrides the realtime state all viewports until RemoveViewportsRealtimeOverride is called. The state of this override is not preserved between editor sessions.
void SetViewportsRealtimeOverride ( bool bShouldBeRealtime, [FText](API\Runtime\Core\Internationalization\FText) SystemDisplayName )